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Plasma Cutting

Plasma Cutting

Plasma cutting was a method developed in the 1950s for cutting metals that could not be cut by oxy-fuel cutting. Such materials include stainless steel, aluminium and copper.  Subsequently, as the method has been refined, it has also been used for the cutting and precision cutting of mild and low-alloyed steel.

Plasma is a state of matter in which the gas is ionised. This means that it consists of positive ions and electrons, causing the media to be electrically conductive. Plasma is very energy-rich. Plasma melts materials locally by means of a constricted plasma gas jet being focused through a nozzle. The molten material being removed from the cut by means of an assist gas.

Plasma cutting is a melt-cutting method, where the energy of the hot plasma arc is used for blowing away molten material. This is carried out using gases adapted to the specific application. For example, mild steel is often cut with oxygen or nitrogen as plasma gas, while stainless steel is often cut with an argon (or nitrogen) based gas, which includes hydrogen as a reducing medium, e.g. Argon/35% Hydrogen

Typically, the gas or gases used are determined by the specification of the plasma machine being used and the material being cut. 

The range of gases commonly used is broad based and the system manufacturers instructions should always be followed.  The table below shows some of the typical gases and their common plasma applications:

Gases Role in Process Material Cut Thickness
Oxygen Cut & Assist Carbon Steel, Stainless Steel & Aluminium < 30 mm
Nitrogen Cut, Start & Assist Carbon Steel, Stainless Steel & Aluminium < 75 mm
Compressed Air Cut & Assist Carbon Steel, Stainless Steel & Aluminium < 25 mm
Argon / 35% Hydrogen Cut Stainless Steel & Aluminium > 75 mm
Nitrogen / 5% Hydrogen Cut Stainless Steel & Aluminium > 50 mm

Struggling to select a gas? If in doubt, please call 0191 271 4888 for specialist advice!

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